Reforming of carbon resources, such as methane in natural gas, coal, petcoke, and biomass, can produce synthesis gas or syngas that is a mixture of hydrogen and carbon monoxide. Catalytic reactions during Fischer-Tropsch (FT) synthesis then convert the syngas into paraffinic hydrocarbons. Hydroprocessing of the paraffinic hydrocarbons produces useful liquid fuels, such as diesel.
Conversion of the syngas into the paraffinic hydrocarbons may utilize various prior FT catalysts. Examples of the catalyst include a Group VIII metal, such as cobalt, on a suitable support. Sulfur can poison such cobalt-based catalysts causing undesirable loss in activity. Preventing sulfur contamination in past approaches ensures the catalyst does not require premature reclaiming by removal of the sulfur from the catalyst upon the activity being diminished below an acceptable level by sulfur poisoning.
The catalysts used can also result in producing byproducts including olefins and oxygenates during reaction of the syngas. Prior to hydrocracking to lower chain paraffins, the byproducts require additional expensive and hydrogen consuming processing into corresponding paraffins Hydrotreating expenses thus depend on selectivity of the FT catalysts to produce the paraffins since hydrotreating costs increase as the selectivity decreases. Furthermore, a ratio of olefins and oxygenates to paraffins produced tends to vary over a run duration of the catalyst necessitating changes and inefficient operation of the hydroprocessing over time.
Therefore, a need exists for improved compositions for catalysts and methods of synthesizing and using the catalysts to convert syngas into paraffins.